Further purification of soluble, template-specific, RNA-dependent RNA replicase will be undertaken. Electrophoretic analysis in SDS-acrylamide gels will be made towards determining if polypeptides similar to those in purifed elongation factor 1 (EF1) are present in replicase. The relative template efficiency of native, aminoacylated, and chemically-modified viral RNAs will be tested in cell-free transcription reactions. If EF1 is part of the replicase complex, then, under conditions where EF1 is limiting, the aminoacylated viral RNA may prove to be a superior template because of its ability to bind elongation factor. Infection of protoplasts with individual RNA components of the multicomponent brome mosaic virus will be carried out to determine the nature of the transcription and translation products of these RNAs. It is expected that only the component(s) carrying the replicase subunit gene will be replicated, and that addition of this component to other RNA components will result in replication where none occurred before such addition. Similar experiments will be undertaken with aminoacylated and chemically-modified viral RNAs.